This invention relates to a sliding sash type window assembly which comprises a fixed rectangular outer frame securable in a window aperture in a building, upper and lower window units mounted in the fixed outer frame with at least one of said units being movable between an open position and a closed position of the window assembly, and respective rectangular frames for said units arranged to permit a lower horizontal frame member of the upper unit to be located alongside an upper horizontal frame member of the lower unit when the window assembly is closed so that a locking element can lock the frame members to each other and thereby prevent unauthorised attempt at forced opening of the window assembly.
Sliding sash type windows have been supplied with timber frames for many years, in which both the upper and the lower window units are capable of vertical sliding movement (one in front of the other) within guide tracks provided in the outer frame, and usually the upper unit is stepped outwardly of the lower unit i.e. it moves in an outer vertical plane which is spaced from an inner plane in which the lower unit is movable. The lower horizontal frame member of the upper unit is located alongside the upper horizontal frame member of the lower unit when both units are in their closed positions, and a suitable lock e.g. a Fitch lock secures the frame members together to prevent forced opening of the window assembly.
Timber frame window units, and the glazing of the units, are heavy, and therefore to facilitate opening and closing movement of the units, it has been traditional to provide counterweight arrangements comprising lead weights, cords and pulleys. The lead weights move up and down within concealed vertical passages defined behind front facings of the vertical side frame members of the fixed frame, but the cords which transmit tensile loads between the lead weights and the window units necessarily are exposed to view, since they must run down the exposed facings to make connections with anchor points on the side frames of the window units.
It is also known to provide adjustable spring assemblies, to provide counterbalance forces to the weights of the sliding sash window units. However, these are quite complicated, expensive, and can require maintenance over a period of time, which is a serious drawback to potential users.
In order to provide for ease of upward and downward movement of sash window units (bearing in mind that the timber components may change in size with temperature changes, or swelling with moisture ingress), it is usual to provide substantial clearances to the movement of the units within the guide provided in the vertical frame members of the fixed frame. This means that in practice when the units are closed, there are often substantial air gaps between the sash window units and the fixed outer frame, which allow drafts of external air to pass through the gaps and into a room. Also, in windy conditions, the sash units can clatter against each other.
Both of these factors are an inevitable feature of traditional timber designs of sash windows, whether genuinely old installations e.g. for Victorian or earlier eras, or from more modern installations in timber.
However, despite these drawbacks, there is substantial design appeal to customers of traditional designs of timber sliding sash windows, and there is a clear commercial demand for the design appeal of these traditional designs to be made available, but preferably utilising more modern materials and sealing techniques, and particularly extruded PVCU sections fibreglass mouldings or aluminium. However, for some users, the invention may be applied to timber framed windows.
To satisfy this need, initial attempts have concentrated on providing a visual illusion i.e. a simulation of vertically sliding sash window units, and using PVCU material to form the fixed outer frame and also the frames of the sash units mounted therein. To form the illusion, it is necessary to mount the sash units in respective off-set vertical planes, so as to make it appear as if the units could be slid vertically one in front of the other.
However, in practice, the lower unit is usually fixedly mounted in the outer frame, and the upper unit is a xe2x80x9ctop openxe2x80x9d window which can move hingedly outwardly about an upper horizontal hinge axis.
By this illusion, while using modern materials, the appearance of sliding sash window units can be obtained, but without need to provide (a) counterweight arrangements and (b) vertical guide tracks in the side frame members of the fixed frame.
The present invention approaches the task of simulating traditional timber frame sliding sash designs, using modern materials, and in a way which actually replicates the vertical sliding movement of traditional timber designs, but also utilising counterweight arrangements which are technically and/or visually improved over existing arrangements.
According to one aspect of the invention there is provided a sliding sash window assembly which comprises a fixed rectangular outer frame securable in a window aperture in a building, upper and lower window units mounted in the fixed outer frame and at of said units being relatively movable between an open position and a closed position of the window assembly, respective rectangular frames for said units arranged to permit a lower horizontal frame member of the upper unit to be located alongside an upper horizontal frame member of the lower unit when the window assembly is closed and a locking element for locking the frame members to each other in a closed position and thereby preventing unauthorized attempts at forced opening of the window assembly, in which:
(a) the rectangular outer frame has side frame members in which counterweight arrangements are housed and which are operable to control the upward and downward sliding movement of said one movable window unit in said outer frame, the side frame members having facing to conceal the counterweight arrangements from view;
(b) each counterweight arrangement includes an elongate tensile element which is connected at one end to a lower end region of said one movable window unit and which is connected at its opposite end to a load which is housed behind the respective facing whereby one portion of the elongate tensile element is also located behind the facing, and another portion of the elongate tensile element extends upwardly of said lower end region of said one movable window unit and alongside a side frame thereof during raising and lowering movement of said one movable window unit; and,
(c) each elongate tensile element is routed through an aperture in a respective one of the facings which is located generally at the level of the lower horizontal frame member of the upper unit and the upper horizontal frame member of the lower unit in the closed position of the window assembly so that, when in this position, the aperture is concealed from view and the tensile element also is not visible.
According to a second aspect of the invention there is provided a sliding sash window assembly which comprises a fixed rectangular outer frame securable in a window aperture in a building, upper and lower window units mounted in the fixed outer frame and one of said units being relatively movable between an open position and a closed position of the window assembly, and respective rectangular frames for said units arranged to permit a lower horizontal frame member of the upper unit to be located alongside an upper horizontal frame member of the lower unit when the window assembly is closed so that a locking element can lock the frame members to each other and thereby prevent unauthorized attempts at forced opening of the window assembly, in which:
(a) the rectangular outer frame has side frames in which counterweight arrangements are housed and which are operable to control the upward and downward sliding movement of said one movable window unit in said outer frame, the side frames having facings to conceal the counterweight arrangements from view;
(b) each counterweight arrangement includes a load connected to an elongate tensile element and which is engageable with a lower end region of said one movable window unit, wherein the elongated tensile element is made of at least one of a belt and a web which is formed from at least one of a plastics material and a reinforced plastics material; and,
(c) each elongate tensile element is routed through an aperture in a respective one of the facings which is located generally at the level of the lower frame member of the upper unit and the upper frame member of the lower unit in the closed position of the window assembly so that, when in this position, the aperture is concealed from view and the tensile element also is not visible, and the elongate tensile element is taken below the lower frame member of said one movable window unit, and each end of the elongate tensile element is connected to a respective counter weight whereby the two counterweights apply an upward force to said movable window unit via the engagement of the elongate tensile element with the lower frame member.
Therefore, a window assembly according to this one aspect of the invention has the advantage of being able to simulate traditional timber designs of sash windows if required, but usually without the unsightly aspect of having the elongate tensile element exposed to view when the assembly is in the closed position. The rectangular outer frame, and the frames of the upper and lower units may be of plastics material, e.g. PVCU, aluminium or timber.
For some embodiments of the invention the load of each counterweight arrangement comprises a stack of at least two weights which are capable of being fed through an entrance aperture into the respective housing in order to be mounted therein for vertical sliding movement.
Therefore, a window assembly according to the second aspect of the invention has an easily installed counterweight arrangement, in that each counterweight arrangement of at least two weights allows easy installation of the counterweight via the aperture.
The frames of the window assembly may be made of plastics e.g. PVCU, fibreglass, aluminium or timber.
Preferably, the aperture is located at the level of the lower frame member of the upper unit and the upper frame member of the lower unit in the closed position of the window assembly so that, when in this position, the aperture is concealed from view and the tensile element also is not visible. However, entrance apertures may be provided in other ways. In one preferred arrangement, the weights forming the stack are fed one by one through an opening in the top of the respective side frame. Alternatively, an entry aperture may be provided in any part of the housing in which the counterweight assembly is vertically slidably movable, and such entry aperture is preferably capable of being covered by a removable cover flap.
In either aspect of the invention, preferably both the upper and lower window units are vertically movable, in respective off-set planes, within guide tracks defined for the window units by the vertical side frame members of the fixed outer frame. However, it is within the scope of the invention for one of the window units to be permanently fixed, and the other one to be vertically slidable.
Cleaning of the inner and outer faces of the window glass of sliding sash windows can be carried out by a cleaner from the inside of the window frame, by sliding movement of the units to gain access to the surfaces to be cleaned, or by use of a ladder to gain access to the outer surfaces, but cleaning by these means can be a tedious task. There is therefore a need to provide a facility whereby the inner and outer surfaces can be readily cleaned by a cleaner standing on the inside of the window frame. This requirement is particularly important to occupants of high rise buildings. Accordingly, in preferred development of the invention, means is provided to allow such cleaning to take place from internally of the fixed frame. This may be obtained by providing a horizontal hinge axis for the lower window unit, which can be activated so as to allow inward pivoting of the lower unit about a hinge axis generally in line with a lower horizontal frame member of the window unit. A limit to the inward pivoting movement may be provided in the form of a stay.
Conveniently, part of the guide tracks on the side frame members of the fixed frame can be disabled, or moved to an inoperative position, thereby allowing inward pivoting movement of the lower window unit and which then allows easy cleaning of the inner and outer surfaces of the lower unit.
The upper window unit will usually be left in an upper position while cleaning of the lower unit takes place, and then the upper unit can be slid downwardly and then also be pivoted inwardly so as to overlie, and preferably at least partly supported by the lower unit, so that its inner and outer surfaces can be cleaned.
The preferred plastics material from which the outer frame and the frames of the window units can be made is extruded PVCU, and provided with metal internal reinforcement as may be required.
The elongate tensile element to connect each counterweight to the respective anchor point of a window unit is preferably made from a strong belt or web of plastics, or reinforced plastics material.
The engagement of the web with the lower edge region of the movable window unit may comprise a secure connection of a free end of the web to a side frame member of the movable unit.
Alternatively, the web may be taken below the lower frame member of the movable unit, and with each end of the web being connected to a respective counterweight whereby the two counterweights apply an upward force to the movable window unit via the engagement of the web with the lower frame member.
Each counterweight may be formed of a stack of two or more weights, introduced one by one into the housings through a suitable entrance aperture e.g. the same aperture through which the web is taken. However, the webs may also be introduced into the housings through another aperture (which is subsequently closed upon completion of the assembly).
Each web may carry an anchor at one end, and a stack of weights can be introduced one by one to form a stack of weights supported by the anchor. The stack of weights may be formed by a cartridge belt type of assembly of at least two weights flexibly connected to each other.
Alternatively, the stack of weights may be arranged one above the other (without any mechanical interconnection), and guided to move up and down within the respective housing by the walls of the housing.